Blade guide for a device for dispensing of paper sections

ABSTRACT

The invention relates to a device for dispensing of paper sections, which has a rotatable roller ( 1 ) provided with a slot ( 4 ), and a blade ( 5 ) arranged in the roller ( 1 ). The blade ( 5 ) is arranged on a carrier ( 7 ) pivotable inside the roller ( 1 ) and can be moved outwardly through the slot ( 4 ) to separate each paper section respectively across one part of the roller turn. A four-bar linkage is used to guide the blade ( 5 ) which is either articulated to the pivotable carrier ( 7 ) and displaceable in a slide guide ( 8 ) or articulated to two carriers ( 7, 9 ) tiltable about parallel axes ( 11, 12 ).

The invention relates to a blade guide for a device for dispensing paperpieces, with a rotatable roller provided with a slit and over which apaper web is conveyed, and with a blade which is arranged on a carrierpivotable inside the roller and which is outwardly moveable through theslit for a part of the rotation of the roller for forming a tear-offperforation in the paper web.

Such devices, which are used in particular as paper towel dispensers insanitary facilities, are known, for example, in different embodimentsfrom DE-A 28 14 792. In FIGS. 12 and 13 of the DE-A document, the bladeprojects approximately perpendicularly from the carrier, wherein, whenviewed from an end face, an overall hook-like shape is produced. Thecarrier is composed of two arms which are pivotally mounted close to theperipheral wall of the roller, respectively in an end wall of theroller, about a common axle which, viewed in the direction of rotation,lies in front of the slit. When the roller is rotated, the blade movesin an arc of a circle through the slit, wherein the carrier lies eitheron a stationary plate cam or is driven by a crank arm which is mountedon a stationary axle parallel to the roller axle. FIGS. 10 and 11 ofDE-A 28 14 792 show an embodiment in which the blade is rotatablymounted on an axle parallel to the roller axle and, guided by the slitin the roller wall, is rotated about the axle. Because of the axlespacing, the blade then projects out of the roller over a part of therevolution of the roller.

The blade guide according to DE-C 36 90 545 includes a carriage whichcan be displaced into a diameter of the roller, on which carriage theblade is arranged parallel to the direction of displacement and movesoutwardly through the slit in a straight line.

According to the strength and elasticity of the paper web to be cut,which is guided over a feed-in press roller, the blade roller and afeed-out press roller, it may happen that the blade does not cut throughthe paper web, but instead only lifts it from the blade roller. Theobject of the invention is therefore to provide a blade guide by meansof which the blade additionally tensions the paper web in the directionof the periphery of the roller such that perforation does actually takeplace.

In accordance with the invention, in a first embodiment this can beachieved in that the blade is linked onto the pivotable carrier, and canbe moved in a slideway. In an equally advantageous alternative, theobject can be solved in a second embodiment in that the blade is linkedto two carriers pivotable about parallel axes.

Both embodiments are based on the four-bar linkage principle, in whichthe blade forms the connecting element, wherein in the first embodiment,a second pivotable carrier is replaced with a joint which isdisplaceable in the slideway. In this way the cutter blade can beprovided with a movement other than a straight one or an arc of a circleabout the pivot axle of the carrier, which at first makes it possiblefor it to be pushed out an angle which causes the teeth of the cutterblade to grip the paper web, and it then inclines in the direction ofthe periphery of the roller, wherein the paper web is tensioned suchthat even when the paper web has a high degree of elasticity andstrength, the teeth penetrate it and perforate it.

Preferred embodiments propose that the slideway is configured in an arcof a circle, wherein the radius of the slideway is different from theradius of the pivotable carrier, or that the two pivotable carriers formparallelogram rods.

During one rotation of the roller, in a first part of the revolution ofthe roller, which covers an angle of rotation of, for example, 240°, theblade is pushed out and then withdrawn again, and in the remainingsecond part of the revolution of the roller, which covers the remainingangle of rotation of, for example, 120°, remains withdrawn. In apreferred embodiment, this is achieved in that the pivotable carrier isguided along a fixed curved path which is not in the shape of an arc ofa circle.

The invention will hereinafter be described in more detail, withreference to the attached drawings, without being limited thereto.

In these is shown, in:

FIGS. 1 to 6 schematic views of the blade roller and of the blade guidein a first embodiment, in each case rotated by 60°,

FIG. 7 a part view, at an angle, of the blade guide,

FIG. 8 a schematic end face view of five different positions of theblade movement, and

FIG. 9 a diagram, similar to FIG. 8, of a second embodiment, and

FIGS. 10 to 15 schematic end face views of the blade roller and of theblade guide in a third embodiment, in each case rotated by 60°.

A device for dispensing paper pieces, for example a paper toweldispenser, is provided with a rotatable roller 1 to which the uncutpaper web is fed from a stock roller by means of a feed-in press roller2. The paper web loops around the larger area of the roller 1 andarrives, via the feed-out press roller 3, at the dispensing point. Thepaper pieces can be detached from the paper web as soon as a perforationline is made at right-angles in the paper web by means of a blade 5, inparticular with teeth. For this, during the revolution of the roller 1,the blade rotating with it is pushed out of the roller 1 through a slit4, wherein the blade moves along a path curved in the direction ofrotation of the roller. Even a paper web with a high degree ofelasticity and strength is thus not only lifted up from the roller butis increasingly tensioned until the teeth finally stick in, as the angleof exit, which is at first large, becomes increasingly smaller. In theembodiments according to FIGS. 1 to 9 the tensioning of the paper webthus takes place between the feed-in press roller 2 and the teeth of theblade, which project from the roller in the direction of revolution ofthe roller. In the embodiment according to FIGS. 10 to 15, thetensioning of the paper web takes place between the feed-out pressroller 3 and the teeth of the blade, which project from the roller inthe direction opposite the direction of rotation of the roller. In theembodiments according to FIGS. 1 to 8, and 10 to 15, the blade guidenecessary for this includes a carrier 7 pivotable about an axle 11,which carrier is composed of two arms, respectively coupled to an endplate 16 of the roller, and a blade holder 6 joining them in anarticulated manner, and a slideway 8 which is composed respectively oftwo bars projecting from the inside surfaces of the end plates 16, inparticular curved bars, between which a guide pin 13 engages. A slit 15in each end plate 16, concentric to the axle 11, is passed through by aguide stud 14 which engages in a fixed curved path 10, which isconfigured according to the desired movement of the blade 5. The curvedpath 10 runs such that in the area with a smaller angle, between thepress rollers 2 and 3, the cutter blade lies inside the slit 4 in theroller 1 (FIGS. 6, 15), and in the area with a larger angle goes out andthen withdraws (FIGS. 1 to 5, 10 to 14).

The movement, in kinematic reversal, of the blade can be seen from FIG.8, when the roller 1 is held and the curved path 10 is rotated about theroller axle.

In the embodiment according to FIG. 9, the blade guide is made by twopivotable carriers which respectively comprise a pair of arms coupled tothe end faces 16. As shown, the carriers 7, 9 can be arranged, havingthe same length and being parallel to one another, in the manner of aparallelogram guide. However, when a path of the cutter blade which isnot in the shape of an arc of a circle is desired or necessary, they canalso be varied in their lengths and spacings. In this embodiment also, acarrier 7 is provided with two guide studs 14 engaging in the fixedcurved paths 10, which pass through the slits 15 in the end faces 16.

What is claimed is:
 1. A blade guide for forming a tear-off perforationin a paper web, when the paper web is being conveyed through a devicefor dispensing paper pieces, said blade guide comprising: a rotatableroller provided with a slit over which the paper web is conveyed; a pairof endplates mounted on said rotatable roller; a blade which outwardlymoves through the slit of said rotatable roller during a part of therotation of said roller by action of a two bar linkage comprising: ablade carrier composed of two arms upon which said blade is pivotallymounted to each of said arms forming a connecting element between eachsaid arm; an axel for each said arm, to which each said arm is pivotallymounted respectively to both said endplate and pivotally mounted withinsaid rotatable roller; a slideway formed within said endplate of saidrotatable roller in which a portion of said blade is guided; a guide pinmounted to said blade which engages said slideway; a curved path whichguides said blade carrier and said blade outwardly through the slit ofsaid rotatable roller during a part of said rotation of said roller;and, a guide stud mounted to each said arm which lies within and followssaid curved path causing movement of said blade through said rotatableroller during part of the rotation.
 2. The blade guide of claim 1wherein said slideway is in the shape of an arc of a circle having afirst radius, and each of said blades have a second radius of motion,and wherein said first radius differs from said second radius.
 3. Theblade guide of claim 2 wherein said blade moves along a path curved inthe direction of the rotation of the roller.
 4. The blade guide of claim2 wherein said blade has a movement other than a straight one whichcauses said blade to grip the paper web and then incline in thedirection of the periphery of said roller.